The present invention relates to highly alkaline proteases optimized by directed mutagenesis of DNA sequences coding for highly alkaline proteases, to DNA sequences (genes) which code for these proteases, to vectors which contain these DNA sequences, and to microorganisms transformed with these vectors, to a process for preparing optimized highly alkaline proteases, and to detergents containing the optimized proteases.
Highly alkaline proteases are valuable industrial products with advantageous applications, especially in the detergent industry, because they remove protein-containing impurities. In order to be effective, these proteases must not only have proteolytic activity under the laundering conditions (pH, temperature) but additionally be compatible with other detergent ingredients, that is to say in combination with other enzymes, surfactants, builders, bleaching agents, bleaching agent activators, and other additives and auxiliaries, that is to say display an adequate stability with respect to the latter and an adequate activity in the presence of these substances.
Highly alkaline proteases are special enzymes which are obtained by cultivation of microorganisms, especially by cultivation of Bacillus species which, like, for example, Bacillus alcalophilus, produce the desired highly alkaline protease and excrete it into the culture medium, from which the protease can be isolated. These highly alkaline proteases differ from usual alkaline proteases as can be obtained by cultivation of Bacillus species such as, in particular, for example B. subtilis, B. amyloliquefaciens and B. licheniformis.
Although many attempts have been made in the prior art to obtain novel highly alkaline proteases with desired properties, and a number of natural and artificially modified (by genetic engineering) alkaline and highly alkaline proteases have been disclosed, there is still a need for novel, optimized highly alkaline proteases, especially highly alkaline proteases optimized with regard to washing properties.